Expressing "not very" with "bu zenme"
When you use 不怎么 (bù zěnme) before an adjective, it means "not very." You might use it to say something like "not very good."
When used together with an adjective, 不怎么 becomes similar to 不太, which means that the degree of the adjective is not very high.
Subj. + 不怎么 + Adj. / [Psychological Verb]
Using this grammar structure is a way to indirectly or mildly state something. Instead of saying 他不聪明 (tā bù cōngming) you can say 他不怎么聪明 (tā bù zěnme cōngming), turning a very direct statement to a milder, more inoffensive comment.
- 最近 不 怎么 忙 。It hasn't been very busy lately.
- 这里 的 冬天 不 怎么 冷 。It's not very cold here in winter.
- 他们 好像 不 怎么 高兴 。They don't seem to be very happy.
- 这个 学生 不 怎么 努力 。This student isn't very hard-working.
- 那 家 餐厅 不 怎么 干净 。That restaurant isn't very clean.
- 这个 老师 不 怎么 专业 。This teacher isn't very professional.
- 你 是 不 是 昨天 睡 得 不 怎么 好 ？Did you not sleep very well last night?
- 我 不 怎么 喜欢 咖啡 。I'm not very into coffee.
- 他 跟 他 父母 长 得 不 怎么 像 。He and his parents don't look very much alike.
- 他 去 美国 一 年 多 了 ，不过 不 怎么 想家 。He's been in the USA for more than one year, but he's not very homesick.
Remember that to make 不怎么 mean "not very" you need to use it with an adjective. Using it with a verb will give it the meaning of "not often."
Sources and further reading